Feed Management

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Feed Management

• MARI-5314
• Dr. Joe Fox

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Feed Appearance

• Feeding behavior of aquatic animals is usually
  associated with some quality of the feed
• odor, palatability, texture, appearance, size
• bottom line a nutritionally-balanced feed is of
  little value if not consumed
• often, the animal must be attracted to the
  particle
• example shrimp feeds w/attractants
• leached attractants are detected through
  chemoreceptors located throughout their body

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Attractability/Pallatability

• Shrimp, unlike fish, feed by olfaction, not by
  sight
• fish cue on color, appearance, movement, all
  vision-related
• attractants fish meal, fish oils, krill meal,
  shrimp head meal, Artemia meal
• feeds with added attractability should bring the
  target animal immediately to the pellet
• without binders, attractants leach out in 2 hr
• if not consumed by then, forget it

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Attractability/Palatability

• Common misconception if farmer can smell
  attractant, the feed is good
• again, we dont smell what they smell
• palatability is particle picked-up and then
  consumed/ingested?
• Regards texture and handling ability of pellet
• shrimp need this more than fish because they are
  sloppy eaters!!

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Pellet Stability

• In the past, farmers thought the longer the
  pellet stability, the better the feed..
• We now recognize that if a pellet has lost its
  attractability, it will not likely be eaten
• the key is to provide the right combination of
  attraction and stability
• accomplished via binders, but expensive
• normal stability around 4-6 hrs
• determined by dry matter, immersion, fractures,
  etc.

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More on Appearance

• Because some aquatics feed by smell, color is
  often irrelevant (REM??)
• however, color can give you an idea of the
  nutrient composition and manufacturing quality of
  the pellet
• pellet color should be uniform, few large
  ingredient particles
• shrimp, unlike fish, can remove tiny ingredient
  particles and discard them

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Feed Pellet Size

• What feed pellet size you feed is determined by
  age of animal
• size of particle must be the one most efficient
  for location and consumption by animal
• proper nutrient package, right size,
  well-distributed
• smaller pellets usually imply easier distribution
• feed particles range in size from less than 50 µM
  to over 1/8 in. diameter

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Feed Pellet Size

• larvae lt50, 50-125, 250, 500 µM, according to
  larval substage
• postlarvae flakes, fine crumbles (500 µM)
• juveniles to 2-3 g medium crumble (1mm) to
  coarse crumble (2mm)
• 3-6 g short pellet (3/32 x 2-4 mm)
• 6-10g medium pellet (3/32 x 6 mm)
• 10-16 g long pellet (3/32 x 10 mm)
• over 16 g 1/8 in. diam, various lengths
• point one pellet per shrimp per feeding

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General Comments

• Now that you have an idea of how feeds are
  formulated and produced, we will discuss feed
  storage, management and application
• three important issues proper-sized pellet,
  nutritionally-balanced, right place/time
• how this is accomplished depends on 1)
  schooling behavior, 2) migratory behavior, 3)
  nutrient requirements, 4) physiology

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Proper Feed Storage

• Because feeds contain ingredients that are
  susceptible to degradation, you are concerned
  with storage conditions and shelf life
• What breaks down? Vitamins, lipids, proteins
• fats and oils break down via rancidification
• proteins can become deaminated do not use any
  feed over 3 months old
• big problem for those who import feed

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Proper Feed Storage

• Watch out if your are importing!! delays
• Delays can turn feed into high-priced fertilizer
  or make it downright toxic!
• Feed typically shipped in 100 lb bags
• sea freight or over-land trucking
• normal shipment 450 x 100 lb bags in one 40 ft
  container
• if mill is nearby shipment is a granel or
  loose-pelleted
• a granel would imply that the farm has a silo and
  bagging system

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Proper Feed Storage

• Feed bags are made of many materials
• paper on outside, plastic liner
• continuous plastic (no weave, no air holes)
• woven polymer
• typically contain labels stating feed type,
  pellet size, proximate analysis, ingredients,
  date of manufacture, etc.
• must be unloaded immediately and placed in proper
  storage

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Proper Feed Storage

• Feeds should be stored in a dry, cool and
  well-ventilated area
• spoilage will occur immediately if feeds become
  wet temperature needs to be consistent
• bags stored on wooden pallets, not on floor
• no more than 5 bags high between pallets
• allows for adequate air circulation between bags,
  constant or similar moisture, temp

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Proper Feed Storage

• Do not store bags directly on concrete floors or
  touching walls of building
• surfaces are often cooler than the bag moisture
  migration
• feed moisture (around 8-12) will migrate to the
  cool area, accumulate
• this encourages growth of molds (REM
  Aspergillus flavius, aflatoxin??)
• also avoid direct sunlight diurnal temperature
  flux

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Proper Feed Storage

• Direct sunlight will adversely affect the vitamin
  and lipid quality of the feed
• do not store feed more than 3 months post
  manufacture
• feeds should be purchased, delivered, and
  utilized on a monthly basis (2-3 containers per
  month for large farms)
• spoiled, wet or old feeds cannot be used
• economic loss of feeding deficient feed may be
  greater than cost associated with discarding it

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Feeding of Shrimp

• The main issues regarding the feeding of shrimp
  are the following
• 1) growth rate
• 2) feed rate
• 3) pellet size
• 4) feed frequency
• 5) feed management

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Growth of Penaeid Shrimp

• Growth of penaeid shrimp is quite fast,
  especially during the juvenile phase, right after
  stocking
• in some cases, it can exceed 1000 per wk
• growth curves describing weight gain of shrimp
  are developed in terms of percent weight gain per
  day, or over any period of time
• growth rate varies throughout life cycle

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Growth of Penaeid Shrimp

• Growth of young shrimp is typically logarithmic
  or exponential until 0.5-1.0 g
• afterwards, it normally becomes linear
• REM just because weight is increasing, does not
  mean biomass is increasing
• many times growth will be slow and then increase,
  sometimes stop
• must be confirmed by biomass/population sampling

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Growth of Penaeid Shrimp

• When viewing growth curves, it is important to
  note that they seldom appear as in the classical
  representations
• they appear more like jagged lines reflecting
  sudden increases/decreases in mean body weight
• attributed to molt status or sampling error
• in the first two days post-molt, shrimp can gain
  1-1.5 g in weight

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General Feeding Guidelines

• The smaller the shrimp, the higher the percentage
  body weight fed as feed/day
• juveniles (less than 0.5 g) are fed up to 50 of
  their body weight per day
• the percentage decreases with weight of shrimp
• as stocking density increases, most farmers
  increase overall feeding rate for entire
  production cycle

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Specific Feeding Guidelines
Note this is just an example, can vary with
stocking density
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Estimation of Feed Usage in Shrimp Ponds
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Feeding of Penaeid Shrimp

• The actual feeding guideline assumes a specific
  growth rate according to season, species of
  shrimp
• L. vannamei dry season 0.5 g/wk, wet season 1.5
  g/wk
• L. stylirostris dry season 1.5 g/wk, wet season
  1.5 g/wk (poor survival)
• has a targeted weight of shrimp to be harvested
  based on experience, investment requirements and
  market price
• must play around with it
• Can it be followed? Not usually.

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Feed Management

• It is very difficult and often impractical to
  follow a feeding guideline
• often not advisable
• only used as a general range for weight
• fine tuning/management comes from estimation of
  feed consumption/biometry
• this is undertaken through use of feeding trays
  and population sampling

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Pond Biomass Sampling

• Determines overall population of shrimp in ponds
• uses cast nets (no other method available)
• cast net size 8-10 ft diameter (3 m)
• mesh size 1/8 in. (0-5 g), 1/4 in. (5g)
• pond matrix developed, sampled as an X
• sampled at night (even distribution), new moon
• at least 20 casts (can be determined by CV)
• population (count/cast net area/spread
  coefficient) x total pond area

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Feeding Trays

• Developed back in the 80s as a spin-off of the
  intensification of shrimp farming in Taiwan
• overfeeding was causing problems with pond water
  quality
• originally placed a portion of feed on tray and
  estimated appetite/consumption by refused
  portion after a period of time
• now-a-days used to feed entire pond

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Feeding Trays

• Method 1 if you are just evaluating
  consumption, use a small number of trays, evenly
  distributed throughout the pond
• semi-intensive 2/ha, intensive 6/ha
• trays are 60-75 cm diameter, ring weighted, use
  about 2 mm mesh on bottom
• add 150 g feed, read refused portion after 2 hrs
• estimate as a percentage of total, record as a
  simple number (0,1,2,3) and compare to a chart
  recommending modifications

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Feeding Tray Guideline

• No residual feed 0 50 increase
• 0-10 residual 1 25 increase
• 10-25 residual 2 10 increase
• 25-50 residual 3 no change
• 50-75 residual 4 decrease 25
• 75-100 residual 5 no feed
• issue workers must be trained to observe
  residual, must correlate dry feed weight to wet
  feed volume in samplers

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Peruvian-style Feeding Trays

• By this method, all feed applied to trays
• trays are large, 3m x 3m, 10 trays/ha
• advantage very accurate consumption information
• advantage all waste accumulates near tray
• advantage FCR will drop 25-35
• disadvantage 100 trays/10 ha pond 3,000 trays
  per farm, 100 trays/worker/day
• issue Is this cost effective?

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Feeding Schedule

• Shrimp are most active and well-distributed at
  night
• daytime poor distribution, less activity
• feeding times 0500 (25), 1900 (25), 000
  (50)
• pay very close attention to where shrimp are at
  these times and whether molting
• feeding times often have to be adjusted to allow
  for only one group of feeders

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Feeding Frequency

• Most farms feed only twice per day until 4-5 g,
  three times per day afterwards
• nutrition available in feed is enhanced by more
  frequent feedings
• translates into better weight gain
• also implies more cost in effort, not practical
  for most farms
• also causes problems in terms of pellet
  distribution

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Feed Distribution

• Distribution of feed to shrimp is just as
  important as nutrition and amount
• poor distribution means poor growth, wasted
  energy on part of the shrimp, economic loss to
  farm
• must understand migratory behavior and
  physiological response
• must feed where the shrimp are
• each pond different
• time of day, entrance of water into pond,
  turbidity, etc. are all important

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Feed Distribution

• In other words, study the pond
• know where to put the feed
• usually broadcast by hand from boats in a zig-zag
  pattern
• also distributed by blowers on trailer, if ponds
  small enough, wind OK
• blowers 4,000 lb capacity, 45 ft throw
• equipped with balances for proper dosage,
  programmable hoppers w/scales

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Other Means of Feed Distribution
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Other Means of Feed Distribution